problem-008.rb

#!/usr/bin/ruby

# Find the greatest product of five consecutive digits in the 1000-digit number


sequence = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"
sequence_array = sequence.split("")
sequence_array.map! { |n| n.to_i }
max_product = 0
(0..sequence_array.size-5).each do |i|
  product = sequence_array[i]*sequence_array[i+1]*sequence_array[i+2]*sequence_array[i+3]*sequence_array[i+4]
  if product > max_product
    max_product = product
  end
end

puts "Answer: " + max_product.to_s